Total reserve balances maintained is the amount of balances institutions hold in accounts at Federal Reserve Banks that are available to satisfy reserve requirements. Historically, this series excluded balances held in a reserve account for contractual clearing purposes (contractual clearing balances program has been discontinued on July 12, 2012).

Effective February 2, 1984, reserve computation and maintenance periods have been changed from weekly to bi-weekly. Series with data prior to February 2, 1984 have different values reported from one week to the next. After February 2, 1984, the value repeats for 2 consecutive weeks.